The O'Brien test, also known as the active compression test, is a physical examination technique primarily used to assess shoulder pain, specifically in relation to the Acromioclavicular (AC) joint and the labrum. It was developed to help identify the source of a patient's shoulder pain after they've demonstrated what movements trigger it.
Understanding the O'Brien Test
The O'Brien test is a provocative maneuver that aims to reproduce the patient's symptoms. It is performed by having the patient:
- Flex their affected arm to 90 degrees, with the elbow fully extended.
- Adduct the arm horizontally across the body by approximately 10-15 degrees.
- Internally rotate the forearm so the thumb is pointing downwards towards the floor.
- Apply downward force by the examiner while the patient resists.
- The process is repeated with the forearm externally rotated, or palm up.
How the Test Works
The test relies on comparing the pain responses in the two different forearm positions. If the patient experiences pain in the internal rotation position that is reduced or eliminated in external rotation, this may indicate a positive test. According to the reference provided, O'Brien found that the test was excellent not only for identifying AC joint pathology, but also for detecting labral issues.
Interpreting the Results
| Test Result | Possible Indication |
|---|---|
| Pain with internal rotation, decreased pain with external rotation | Potential labral tear. Potential AC joint pathology. |
| Pain present in both positions | Non-specific shoulder pathology or issues not related to labrum or AC joint. |
| No pain in either position | Negative test, potentially ruling out labral and AC joint problems. |
It is important to note that the O'Brien test should always be used in combination with other clinical findings and is not a definitive diagnostic tool. A positive test should warrant further investigation like advanced imaging (MRI), for a confirmed diagnosis.
Clinical Significance
- AC Joint Assessment: O'Brien's active compression test is often used to assess issues of the Acromioclavicular joint, a common source of shoulder pain.
- Labral Tear Detection: This test is also very effective in detecting labral tears in the shoulder, especially when patients experience pain with the arm internally rotated, as stated in the provided reference.
- Differential Diagnosis: The test helps in differentiating shoulder pain related to the labrum and AC joint from other soft tissue or muscular issues.
In Conclusion
The O'Brien test is a valuable clinical tool for assessing shoulder pain, primarily focusing on labral and AC joint issues. It involves a set of specific arm positions and resistance, where pain reproduction is noted. A detailed clinical evaluation combined with imaging is necessary for accurate diagnosis.
